Mühendislik ve Doğa Bilimleri Fakültesi Koleksiyonu

Permanent URI for this collectionhttps://hdl.handle.net/20.500.13091/1624

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Citation - WoS: 14
Citation - Scopus: 16
Cognitive Networks in the Presence of I/Q Imbalance and Imperfect Csi: Receiver Design and Performance Analysis
(IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2019) Alsmadi, Malek Mohammad; Canbilen, Ayşe Elif; Abu Ali, Najah; Ikki, Salama Said; Başar, Ertuğrul
Future wireless communication systems, including fifth-generation (5G) networks and the Internet of Things (IoT), require a massive number of inexpensive transceivers. These transceivers come with various hardware impairments, such as phase noise and in-phase/quadrature phase (I/Q) imbalance. This piece of work studies the performance of underlay cognitive radio (CR) networks, considering the joint effect of I/Q imbalance and imperfect channel-state information (CSI) at the secondary user. In order to mitigate the effect of I/Q imbalance, an optimal maximum likelihood (ML) receiver design is proposed and analyzed. Specifically, a closed-form expression of the average pairwise error probability (APEP) and a tight upper bound of the average bit error rate (ABER) are derived. In addition, a widely linear equalization (WLE) receiver that has performance close to the optimal receiver with a computational complexity close to the traditional blind receiver is proposed. In particular, the exact PEP of this WLE receiver is obtained and its APEP is calculated numerically. Moreover, an exact expression is derived for Cramer-Rao lower bound (CRLB) of the secondary system receiver channel estimation error in the presence of I/Q imbalance at the secondary transmitter/receiver (STx/SRx) sides. Computer simulations prove the analytical results of the proposed receivers. The obtained results show that the optimal receiver has the best performance and the WLE receiver outperforms the traditional ML receiver in most cases. In addition, the analysis shows that the best estimator that reaches the CRLB is not affected by the I/Q imbalance at STx/SRx.
Citation - WoS: 4
Citation - Scopus: 5
Effect of Generalized Improper Gaussian Noise and In-phase/Quadrature-phase Imbalance on Quadrature Spatial Modulation
(IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2021) Alsmadi, Malek M.; Canbilen, Ayşe Elif; Abu Ali, Najah; Ikki, Salama Said
Quadrature spatial modulation (QSM) isa recently proposed multiple-input multiple-output (MIMO) wireless transmission paradigm that has garnered considerable research interest owing to its relatively high spectral efficiency. QSM essentially enhances the spatial multiplexing gain while maintaining all the inherent advantages of spatial modulation (SM). This work studies the effects of in-phase/quadrature-phase (I/Q) imbalance and improper Gaussian noise (IGN) on the performance of QSM. Considering a scenario where both receiver and transmitter operate under the effects of I/Q imbalance, we propose a novel receiver design that optimizes the system bit error rate (BER) when there is IGN at the receiver. Closed forms of the average pairwise error probability (APEP) and upper bound of the average BER formulas are derived. These formulas are derived considering the Beckmann fading channel model, where most well-known fading channel models can be considered special cases. The proposed designs demonstrate solid performance despite the effects of I/Q imbalance. In fact, these effects can be entirely eliminated if they exist at the receiver and significantly reduced at the transmitter. All analytical results were verified by computer simulations.
Citation - WoS: 1
Citation - Scopus: 7
Impact of Channel Correlation and Hardware Impairments on Large Intelligent Surfaces-Aided Communication Systems
(Ieee, 2021) Saleh, Emad; Alsmadi, Malek M.; Bouhlel, Asma; Canbilen, Ayşe E.; Abu Ali, Najah; Ikki, Salama
Large Intelligent Surfaces (LIS) are promising in terms of what they can offer to 6G and beyond communication networks. As such, they have recently attracted considerable attention in the research community. This technique allows the operators to control the environment in a strategic way so as to improve the communication system performance. This work studies the effect of hardware impairments (HWIs) on the LIS-Aided wireless communication system under correlated channel conditions. In specific, we look at the impact on the system performance. We also give a deterministic approximation function of the average bit error rate (ABER) for a large number of reflectors and a tight approximation of the outage probability (OP). Extensive Monte Carlo simulations are provided to verify the analytical results, which show that the system performance saturates at a high signal-to-noise ratio (SNR) due to the HWIs. Moreover, this degradation is exacerbated when the channels demonstrate strong correlation conditions. However, the HWIs have a dominant effect and the correlation impact diminishes with a larger number of reflectors.

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